Field of the Invention
The present invention relates to magnet particles and a magnet molding using same.
Background Information
A rare earth magnet containing a rare earth element and a transition metal has both high magneto crystalline anisotropy and high saturation magnetization, and thus shows promise for various applications as a permanent magnet. Among rare earth magnets, it is known that rare earth-transition metal-nitrogen-based magnets, typified by Sm—Fe—N based magnets, exhibit excellent magnetic properties without using costly raw materials.
In addition, there are two main types of rare earth magnets that are currently used, sintered magnets and bond magnets. Of these, bond magnets are used by solidifying magnetic powder, having excellent magnetic properties, with resin at room temperature.
Rare earth-transition metal-nitrogen-based magnets, typified by Sm—Fe—N based magnets, show promise as permanent magnets, but have the disadvantage of lacking thermal stability. When a rare earth-transition metal-nitrogen-based magnet is heated to 600° C. or more, the magnet decomposes into rare earth nitrides and transition metals; therefore, it is not possible to produce a magnet molding by the sintering method as with the conventional powder metallurgy method. Therefore, rare earth-transition metal-nitrogen-based magnets have been used as bond magnets, but in this case, since the volume of organic matter (resin) as binder occupies about 30% of the whole, sufficient magnetic force cannot be obtained.
Therefore, in the production of bond magnets for those rare earth magnets that contain a rare earth element and a transition metal, a method of solidification molding is in demand whereby it is possible to obtain a magnet molding that does not contain substances other than the magnetic powder, to the greatest possible extent, without solidifying with an organic substance (binder). As such a solidification molding method, molding processes such as explosion bonding by explosion of an explosive, and HIP (hot isostatic pressing), are known. Of these, HIP (hot isostatic pressing) is associated with poor productivity.
Consequently, as such a solidification molding method, the powder impact molding method using an explosive disclosed in Japanese Laid-Open Patent Application No. Hei 6(1994)-77027 (Patent Document 1) has been evaluated to date.